Phase change inks comprising fatty acids

ABSTRACT

A solid ink composition suitable for ink jet printing, including printing on coated paper substrates. In embodiments, the solid ink composition comprises both a crystalline compound and an amorphous compound, and a fatty acid, which provides for a robust ink wherein the phase change ink crystallizes faster from the liquid state than the same composition without the fatty acid.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly owned and co-pending, U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInk Compositions Comprising Crystalline Diurethanes And DerivativesThereof” to Naveen Chopra et al., electronically filed on the same dayherewith (Attorney Docket No. 20110356-396152); U.S. patent applicationSer. No. ______ (not yet assigned) entitled “Phase Change InkCompositions Comprising Crystalline Sulfone Compounds and DerivativesThereof” to Kentaro Morimitsu et al., electronically filed on the sameday herewith (Attorney Docket No. 20110561-396955); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInks Comprising Crystalline Amides” to Kentaro Morimitsu et al.,electronically filed on the same day herewith (Attorney Docket No.20110665-397243); U.S. patent application Ser. No. ______ (not yetassigned) entitled “Phase Change Ink Compositions Comprising AromaticEthers” to Kentaro Morimitsu et al., electronically filed on the sameday herewith (Attorney Docket No. 20110362-396157); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “FastCrystallizing Crystalline-Amorphous Ink Compositions and Methods forMaking the Same” to Gabriel Iftime et al., electronically filed on thesame day herewith (Attorney Docket No. 20110459-399389); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “RapidSolidifying Crystalline-Amorphous Inks” to Gabriel Iftime et al.,electronically filed on the same day herewith (Attorney Docket No.20110982-399395);U.S. patent application Ser. No. ______ (not yetassigned) entitled “Phase Change Inks Comprising Inorganic NucleatingAgents” to Daryl W. Vanbesien et al., electronically filed on the sameday herewith (Attorney Docket No. 20111206-400896); U.S. patentapplication Ser. No. ______ (not yet assigned) entitled “Phase ChangeInks Comprising Aromatic Diester Crystalline Compounds” to KentaroMorimitsu et al., electronically filed on the same day herewith(Attorney Docket No. 20111040-399927); U.S. patent application Ser. No.______ (not yet assigned) entitled “Phase Change Ink CompositionsComprising Diurethanes as Amorphous Materials” to Naveen Chopra et al.,electronically filed on the same day herewith (Attorney Docket No.20110610-397242); U.S. patent application Ser. No. ______ (not yetassigned) entitled “Phase Change Inks Comprising Organic Pigments” toJennifer Belelie et al., electronically filed on the same day herewith(Attorney Docket No. 20110418-399388); U.S. patent application Ser. No.______ (not yet assigned) entitled “TROM Process for Measuring the Rateof Crystallization of Phase Change Inks” to Gabriel Iftime et al.,electronically filed on the same day herewith (Attorney Docket No.20110828-401275), U.S. patent application Ser. No. ______ (not yetassigned) entitled “Rapidly Crystallizing Phase Change Inks and Methodsfor Forming the Same” to Jennifer Belelie et al., electronically filedon the same day herewith (Attorney Docket No. 20111455-403044); theentire disclosures of which are incorporated herein by reference in itsentirety

BACKGROUND

The present embodiments relate to solid ink compositions characterizedby being solid at room temperature and molten at an elevated temperatureat which the molten ink is applied to a substrate. These solid inkcompositions can be used for ink jet printing. The present embodimentsare directed to a novel solid ink composition comprising an amorphouscompound, a crystalline compound, and optionally a colorant, and methodsof making the same. In particular, the compound is an ester of tartaricor citric acid and the crystalline compound is an ester of tartaricacid.

Ink jet printing processes may employ inks that are solid at roomtemperature and liquid at elevated temperatures. Such inks may bereferred to as solid inks, hot melt inks, phase change inks and thelike. For example, U.S. Pat. No. 4,490,731, the disclosure of which istotally incorporated herein by reference, discloses an apparatus fordispensing phase change ink for printing on a recording medium such aspaper. In piezo ink jet printing processes employing hot melt inks, thesolid ink is melted by the heater in the printing apparatus and utilized(jetted) as a liquid in a manner similar to that of conventional piezoink jet printing. Upon contact with the printing recording medium, themolten ink solidifies rapidly, enabling the colorant to substantiallyremain on the surface of the recording medium instead of being carriedinto the recording medium (for example, paper) by capillary action,thereby enabling higher print density than is generally obtained withliquid inks. Advantages of a phase change ink in ink jet printing arethus elimination of potential spillage of the ink during handling, awide range of print density and quality, minimal paper cockle ordistortion, and enablement of indefinite periods of nonprinting withoutthe danger of nozzle clogging, even without capping the nozzles.

In general, phase change inks (sometimes referred to as “hot melt inks”)are in the solid phase at ambient temperature, but exist in the liquidphase at the elevated operating temperature of an ink jet printingdevice. At the jetting temperature, droplets of liquid ink are ejectedfrom the printing device and, when the ink droplets contact the surfaceof the recording medium, either directly or via an intermediate heatedtransfer belt or drum, they quickly solidify to form a predeterminedpattern of solidified ink drops.

Phase change inks are desirable for ink jet printers because they remainin a solid phase at room temperature during shipping, long term storage,and the like. In addition, the problems associated with nozzle cloggingas a result of ink evaporation with liquid ink jet inks are largelyeliminated, thereby improving the reliability of the ink jet printing.Further, in phase change ink jet printers wherein the ink droplets areapplied directly onto the final recording medium (for example, paper,transparency material, and the like), the droplets solidify immediatelyupon contact with the recording medium, so that migration of ink alongthe printing medium is prevented and dot quality is improved.

While the above conventional solid ink technology is generallysuccessful in producing vivid images and providing economy of jet useand substrate latitude on porous papers, such technology has not beensatisfactory for coated substrates. Thus, while known compositions andprocesses are suitable for their intended purposes, a need remains foradditional means for forming images or printing on coated papersubstrates. As such, there is a need to find alternative compositionsfor solid ink compositions and future printing technologies to providecustomers with excellent image quality on all substrates.

There is further a need to provide such solid ink compositions which aresuitable for fast printing environments like production printing.

Each of the foregoing U.S. patents and patent publications areincorporated by reference herein. Further, the appropriate componentsand process aspects of the each of the foregoing U.S. patents and patentpublications may be selected for the present disclosure in embodimentsthereof.

SUMMARY

According to embodiments illustrated herein, there is provided novelsolid ink compositions comprising a crystalline compound, an amorphous,and a fatty acid for ink jet printing, including printing on coatedpaper substrates and wherein the phase change ink crystallizes fasterfrom the liquid state than the same composition without a fatty acid.

In particular, the present embodiments provide a phase change inkcomprising an amorphous compound; a crystalline compound; and a fattyacid; wherein the phase change ink crystallizes faster from the liquidstate than the same composition without the fatty acid.

In further embodiments, there is provided a phase change ink comprisingan amorphous compound comprises a first ester of tartaric acid ofFormula I

wherein each R₁, and R₂ is independently an alkyl group, wherein thealkyl portion can be straight, branched or cyclic, saturated orunsaturated, substituted or unsubstituted, having from about 1 to about40 carbon atoms, or an substituted or unsubstituted aromatic orheteroaromatic group, and mixtures thereof;

a crystalline compound comprises a second ester of tartaric acid ofFormula III

wherein each R₆ and R₇ is independently selected from the groupconsisting of

and mixtures thereof; and a fatty acid; wherein the tartaric acidbackbone is selected from L-(+)-tartaric acid, D-(−)-tartaric acid,DL-tartaric acid, or mesotartaric acid, and mixtures thereof.

In yet other embodiments, there is provided a phase change inkcomprising an amorphous compound beingbis(2-isopropyl-5-methylcyclohexyl) L-tartrate); a crystalline compoundsselected from the group consisting of dibenzyl L-tartrate, diphenethylL-tartrate, bis(3-phenyl-1-propyl) L-tartrate, bis(2-phenoxyethyl)L-tartrate, diphenyl L-tartrate, bis(4-methylphenyl) L-tartrate,bis(4-methoxylphenyl) L-tartrate, bis(4-methylbenzyl) L-tartrate,bis(4-methoxylbenzyl) L-tartrate, dicyclohexyl L-tartrate, and anystereoisomers and mixtures thereof; and a fatty acid.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present embodiments, reference may behad to the accompanying figures.

FIG. 1 illustrates the TROM process showing images of crystallineformation in an ink base from crystallization onset to crystallizationcompletion according to an embodiment of the disclosure.

DETAILED DESCRIPTION

In the following description, it is understood that other embodimentsmay be utilized and structural and operational changes may be madewithout departure from the scope of the present embodiments disclosedherein.

As used herein, the term “alkyl” refers to an aliphatic hydrocarbongroup. The alkyl moiety may be a “saturated alkyl” group, which meansthat it does not contain any alkene or alkyne moieties. The alkyl moietymay also be an “unsaturated alkyl” moiety, which means that it containsat least one alkene or alkyne moiety. An “alkene” moiety refers to agroup consisting of at least two carbon atoms and at least onecarbon-carbon double bond, and an “alkyne” moiety refers to a groupconsisting of at least two carbon atoms and at least one carbon-carbontriple bond. The alkyl moiety, whether saturated or unsaturated, may bebranched, straight chain, or cyclic.

The alkyl group may have 1 to 40 carbon atoms (whenever it appearsherein, a numerical range such as “1 to 40” refers to each integer inthe given range; e.g., “1 to 40 carbon atoms” means that the alkyl groupmay consist of 1 carbon atom, 2 carbon atoms, 3 carbon atoms, etc., upto and including 40 carbon atoms, although the present definition alsocovers the occurrence of the term “alkyl” where no numerical range isdesignated). The alkyl group may also be a medium size alkyl having 1 to10 carbon atoms. The alkyl group could also be a lower alkyl having 1 to4 carbon atoms. The alkyl group of the compounds of the invention may bedesignated as “C₁-C₅ alkyl” or similar designations. By way of exampleonly, “C₁-C₄ alkyl” indicates that there are one to four carbon atoms inthe alkyl chain, i.e., the alkyl chain is selected from the groupconsisting of methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl,sec-butyl, and t-butyl.

The alkyl group may be substituted or unsubstituted. When substituted,any group(s) besides hydrogen can be the substitutent group(s). Whensubstituted, the substituent group(s) is(are) one or more group(s)individually and independently selected from the following non-limitingillustrative list: alkyl, cycloalkyl, hydroxy, alkoxy, cyano, halo, andamino, including mono- and di-substituted amino groups. Typical alkylgroups include, but are in no way limited to, methyl, ethyl, propyl,isopropyl, butyl, isobutyl, tertiary butyl, pentyl, hexyl, ethenyl,propenyl, butenyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, andthe like. Each substituent group may be further substituted.

The term “aryl,” as used herein, alone or in combination, means acarbocyclic aromatic system containing one, two or three rings whereinsuch rings may be attached together in a pendent manner or may be fused.The term “aryl,” embraces aromatic radicals such as benzyl, phenyl,naphthyl, anthracenyl, and biphenyl.

The term “arylalkyl” as used herein, alone or in combination, refers toan aryl group attached to the parent molecular moiety through an alkylgroup.

Solid ink technology broadens printing capability and customer baseacross many markets, and the diversity of printing applications will befacilitated by effective integration of printhead technology, printprocess and ink materials. The solid ink compositions are characterizedby being solid at room temperature (RT) (e.g., 20-27° C.) and molten atan elevated temperature at which the molten ink is applied to asubstrate. As discussed above, while current ink options are successfulfor porous paper substrates, these options are not always satisfactoryfor coated paper substrates.

It was previously discovered that using a mixture of crystalline andamorphous small molecule compounds in solid ink formulations providesrobust inks, and in particular, solid inks which demonstrate robustimages on coated paper. (U.S. patent application Ser. No. 13/095,636entitled “Solid Ink Compositions Comprising Crystalline-AmorphousMixtures” to Jennifer L. Belelie et al. (Attorney Docket No.20101286-390681) filed Apr. 27, 2011.

Using this approach is surprising, however, due to the known propertiesof crystalline or amorphous materials. For crystalline materials, smallmolecules generally tend to crystallize when solidifying and lowmolecular weight organic solids are generally crystals. Whilecrystalline materials are generally harder and more resistant, suchmaterials are also much more brittle, so that printed matter made usinga mainly crystalline ink composition is fairly sensitive to damage. Foramorphous materials, high molecular weight amorphous materials, such aspolymers, become viscous and sticky liquids at high temperature, but donot show sufficiently low viscosity at high temperatures. As a result,the polymers cannot be jetted from print head nozzles at desirablejetting temperature (≦140° C.). In the present embodiments, however, itis discovered that a robust solid ink can be obtained through a blend ofcrystalline and amorphous compounds.

However, the present inventors discovered that in many cases addition ofa dye colorant to an ink base composition comprised of an amorphous anda crystalline compound typically results in inks which solidify, i.e.,crystallize, too slowly to be useful for fast printing. Furthermore,many ink base compositions made of mixtures of an amorphous and acrystalline components were shown to also solidify too slowly.Solidification of the ink is due to crystallization of the crystallinecomponent in the ink when cooling. The inventors have found that fastcrystallization is not an inherent property of a crystalline-amorphouscomposition. Methods for providing fast crystallizingcrystalline-amorphous inks are not obvious.

The present inventors discovered that addition of a fatty acid additiveto a composition made of crystalline and amorphous components results inacceleration of the crystallization of the ink when cooling from themolten state.

The present embodiments provide a new type of ink jet solid inkcomposition which comprises a blend of (1) crystalline and (2) amorphouscompounds, generally in a weight ratio of from about 60:40 to about95:5, respectively. In more specific embodiments, the weight ratio ofthe crystalline to amorphous compound is from about 65:35 to about 95:5,or is from about 70:30 to about 90:10, or is from about 70:30 to about80:20. In other embodiments, the crystalline and amorphous compounds areblended in a weight ratio of from about 1.5 to about 20, or from about2.0 to about 10, respectively.

Each compound or component imparts specific properties to the solidinks, and the resulting inks incorporating a blend of these amorphousand crystalline compounds demonstrate excellent robustness on uncoatedand coated substrates. The crystalline compound in the ink formulationdrives the phase change through rapid crystallization on cooling. Thecrystalline compound also sets up the structure of the final ink filmand creates a hard ink by reducing the tackiness of the amorphouscompound. The amorphous compounds provide tackiness and impartrobustness to the printed ink.

The Amorphous Compound

In embodiments, the amorphous compound comprises a first ester oftartaric acid of Formula I or a first ester of citric acid of Formula II

wherein each R₁, R₂, R₃, R₄, and R₅ is independently an alkyl group,wherein the alkyl can be straight, branched or cyclic, saturated orunsaturated, substituted or unsubstituted, having from about 1 to about40 carbon atoms. In certain embodiments, each R₁, R₂, R₃, R₄ and R₅ isindependently a cyclohexyl group optionally substituted with one or morealkyl groups selected from methyl, ethyl, n-propyl, isopropyl, n-butyland t-butyl. In certain embodiments, each R₁, R₂, R₃, R₄ and R₅ isindependently a cyclohexyl group or a cyclohehyl group substituted withone or more alkyl groups selected from methyl, ethyl, n-propyl,isopropyl, n-butyl and t-butyl.

Referring to Formula I, in certain embodiments, one of R₁ and R₂ is2-isopropyl-5-methylcyclohexyl, and the other one of R₁ and R₂ is2-isopropyl-5-methylcyclohexyl, 4-t-butylcyclohexyl, or cyclohexyl, orone of R₁ and R₂ is 4-t-butylcyclohexyl, and the other one of R₁ and R₂is cyclohexyl. In certain embodiment, R₁ and R₂ are each2-isopropyl-5-methylcyclohexyl. In certain embodiment, R₁ is2-isopropyl-5-methylcyclohexyl and R₂ is 4-t-butylcyclohexyl. In certainembodiment, R₁ is 2-isopropyl-5-methylcyclohexyl and R₂ is cyclohexyl.In certain embodiment, R₁ is 4-t-butylcyclohexyl and R₂ is cyclohexyl.

Referring to Formula II, in certain embodiments, one of R₃, R₄ and R₅ is2-isopropyl-5-methylcyclohexyl, and the other one of R₃, R₄ and R₅ is2-isopropyl-5-methylcyclohexyl, 4-t-butylcyclohexyl, or cyclohexyl, orone of R₃, R₄ and R₅ is 4-t-butylcyclohexyl, and the other one of R₃, R₄and R₅ is cyclohexyl. In certain embodiment, R₃, R₄ and R₅ are each2-isopropyl-5-methylcyclohexyl. In certain embodiment, R₃ is2-isopropyl-5-methylcyclohexyl and R₄ and R₅ are each4-t-butylcyclohexyl. In certain embodiments, R₃ is2-isopropyl-5-methylcyclohexyl and R₄ and R₅ are each cyclohexyl. Incertain embodiment, R₁ is 4-t-butylcyclohexyl and R₄ and R₅ are eachcyclohexyl.

Some suitable amorphous materials are disclosed in U.S. patentapplication Ser. No. 13/095,784 to Morimitsu et al., which is herebyincorporated by reference in its entirety. The amorphous materials maycomprise an ester of tartaric acid having a formula of

wherein R₁ and R₂ each, independently of the other or meaning that theycan be the same or different, is selected from the group consisting ofalkyl group, wherein the alkyl portion can be straight, branched orcyclic, saturated or unsaturated, substituted or unsubstituted, havingfrom about 1 to about 40 carbon atoms. In certain embodiments, each R₁and R₂ is independently a cyclohexyl group optionally substituted withone or more alkyl group(s) selected from methyl, ethyl, n-propyl,isopropyl, n-butyl and t-butyl. In certain embodiments, R₁ and R₂ areeach 2-isopropyl-5-methylcyclohexyl.

The tartaric acid backbone is selected from L-(+)-tartaric acid,D-(−)-tartaric acid, DL-tartaric acid, or mesotartaric acid, andmixtures thereof. Depending on the R groups and the stereochemistries oftartaric acid, the esters could form crystals or stable amorphouscompounds. In specific embodiments, the amorphous compound is selectedfrom the group consisting of di-L-menthyl L-tartrate, di-DL-menthylL-tartrate (DMT), di-L-menthyl DL-tartrate, di-DL-menthyl DL-tartrate,and any stereoisomers and mixtures thereof.

These materials show, relatively low viscosity (<10² centipoise (cps),or from about 1 to about 100 cps, or from about 5 to about 95 cps) nearthe jetting temperature (≦140° C., or from about 100 to about 140° C.,or from about 105 to about 140° C.) but very high viscosity (>10⁵ cps)at room temperature.

To synthesize the amorphous component, tartaric acid was reacted with avariety of alcohols to make di-esters as shown in the synthesis schemeshown in U.S. patent application Ser. No. 13/095,784. Suitable alcoholsto be used with the present embodiments may be selected from the groupconsisting of alkyl alcohol, wherein the alkyl portion of the alcoholcan be straight, branched or cyclic, saturated or unsaturated,substituted or unsubstituted, having from about 1 to about 40 carbonatoms, or a substituted or unsubstituted aromatic or heteroaromaticgroup, and mixtures thereof. A variety of alcohols may be used in theesterification such as, for example, menthol, isomenthol, neomenthol,isoneomenthol and any stereoisomers and mixtures thereof. Mixtures ofaliphatic alcohols may be used in the esterification. Suitable alcoholsfor mixed reactions include cyclohexanol and substituted cyclohexanol(e.g., 2, 3 or 4-t-Butyl cyclohexanol). For example, a mixture of twoaliphatic alcohols may be used in the esterification. The molar ratiosof the aliphatic alcohols may be from 25:75 to 75:25, from 40:60 to60:40, or about 50:50.

In embodiments, two or more molar equivalents of alcohol may be used inthe reaction to produce the di-esters of tartaric acid. If one molarequivalent of alcohol is used, the result is mostly mono-esters.

Other suitable amorphous components include those disclosed in U.S.patent application Ser. No. 13/095,795 to Morimitsu et al., which ishereby incorporated by reference in its entirety. The amorphousmaterials may comprise a compound having the following structure:

R₃, R₄ and R₅ are independently an alkyl group, wherein the alkyl can bestraight, branched or cyclic, saturated or unsaturated, substituted orunsubstituted, having from about 1 to about 40 carbon atoms

These amorphous materials are synthesized by an esterification reactionof citric acid. In particular, citric acid was reacted with a variety ofalcohols to make tri-esters according to the synthesis scheme disclosedtherein.

The Crystalline Compound

The crystalline compound may comprise a second ester of tartaric acid ofFormula III

wherein each R₆ and R₇ is independently an aryl or a heteroaryloptionally substituted with a lower alkyl and alkoxy, each n isindependently 0 to 3. In certain embodiments, each R₆ and R₇ isindependently an optionally substituted aryl, such as a phenyl. Incertain embodiments, each R₆ and R₇ is independently not substituted, orsubstituted with methyl, ethyl, isopropyl, methoxy or ethyoxy. Incertain embodiments, each R₆ and R₇ is independently a phenyl optionallysubstituted with methyl or methoxy.

In certain embodiments, each R₆ and R₇, independently is selected fromthe group consisting of

and mixtures thereof.In certain embodiments, the tartaric acid backbone is selected fromL-(+)-tartaric acid, D-(−)-tartaric acid, DL-tartaric acid, ormesotartaric acid, and mixtures thereof.

In certain embodiments, the crystalline compound is selected from thegroup consisting of dibenzyl L-tartrate, diphenethyl L-tartrate,bis(3-phenyl-1-propyl) L-tartrate, bis(2-phenoxyethyl) L-tartrate,diphenyl L-tartrate, bis(4-methylphenyl) L-tartrate,bis(4-methoxylphenyl) L-tartrate, bis(4-methylbenzyl) L-tartrate,bis(4-methoxylbenzyl) L-tartrate, dicyclohexyl L-tartrate,bis(4-tert-butylcyclohexyl)-L-tartrate and mixtures thereof.

The crystalline materials show sharp crystallization, relatively lowviscosity (≦10¹ centipoise (cps), or from about 0.5 to about 20 cps, orfrom about 1 to about 15 cps) at a temperature of about 140° C., butvery high viscosity (≦10⁶ cps) at room temperature. These materials havea melting temperature (T_(melt)) of less than 150° C., or from about 65to about 150° C., or from about 66 to about 145° C., and acrystallization temperature (T_(crys)) of greater than 60° C., or fromabout 60 to about 140° C., or from about 65 to about 120° C. The ΔTbetween T_(melt) and T_(crys) is less than about 55° C.

The present embodiments comprise a balance of amorphous and crystallinecompounds to realize a sharp phase transition from liquid to solid andfacilitate hard and robust printed images, while maintaining a desiredlevel of viscosity. Prints made with this ink demonstrated advantagesover commercially available inks, such as for example, better robustnessagainst scratch. Thus, the present esters of tartaric acid, whichprovide amorphous compounds for the solid inks, have been discovered toproduce robust inks having desirable rheological profiles and that meetthe many requirements for inkjet printing.

In the present embodiments, the solid ink composition may also comprisethe crystalline and amorphous material in combination with a colorant.The present embodiments comprise a balance of amorphous and crystallinematerials to realize a sharp phase transition from liquid to solid andfacilitate hard and robust printed images, while maintaining a desiredlevel of viscosity. Prints made with this ink demonstrated advantagesover commercially available inks, such as for example, better robustnessagainst scratch. Thus, the resulting ink compositions comprising a blendof the crystalline and amorphous compounds show good rheologicalprofiles and that meet the many requirements for ink jet printing.

Synthesis of Tartaric Acid

Tartaric acid was reacted with a variety of alcohols to make di-estersas shown in the synthesis scheme below, which illustrates thepreparation of a tartaric acid di-ester compound of the presentembodiments. The esterification was conducted by a one-step reaction:

ROH and R′OH may be the same of different.

To synthesize the amorphous materials, a variety of aliphatic alcoholsmay be used in the esterification such as, for example, menthol,isomenthol, neomenthol, isoneomenthol and any stereoisomers and mixturesthereof. Mixtures of aliphatic alcohols may be used in theesterification. Suitable alcohols for mixed reactions includecyclohexanol and substituted cyclohexanol (e.g., 2, 3 or 4-t-butylcyclohexanol). For example, a mixture of two aliphatic alcohols may beused in the esterification. The molar ratios of the aliphatic alcoholsmay be from 25:75 to 75:25, from 40:60 to 60:40, or about 50:50.

Menthol was the alcohol selected for the experimental data. Bothtartaric acid and menthol have stereoisomers; therefore, there are manypossible combinations in terms of chirality. Three combinations oftartaric acid and menthol (di-L-menthyl L-tartrate, di-DL-menthylL-tartrate, di-L-menthyl DL-tartrate) were synthesized. Surprisingly,all combinations, even in the combination of optically pure L-mentholand L-tartaric acid, made amorphously setting materials which showed nocrystallization. Suitable alcohols to be used with the presentembodiments may be selected from the group consisting of alkyl alcohol,wherein the alkyl portion of the alcohol can be straight, branched orcyclic, saturated or unsaturated, substituted or unsubstituted, havingfrom about 1 to about 16 carbon atoms.

To synthesize the crystalline materials, a variety of aromatic alcoholsmay be used in the esterification. Non-limiting exemplary aromaticalcohols includes the structures shown below

and any stereoisomers and mixtures thereof.

In embodiments, two or more molar equivalents of alcohol may be used inthe reaction to produce the di-esters of tartaric acid. If one molarequivalent of alcohol is used, the result is mostly mono-esters.

Fatty Acid

The ink composition of the present embodiments comprises a fatty acid.Fatty acids may contain carbon chains of about 12 to about 28 carbons,about 16 to about 24 carbons, or about 18 to about 22 carbons. The fattyacid may be saturated or unsaturated. Specific non-limiting examples offatty acids include, but are not limited to, palmitic acid (hexadecanoicacid), palmitoleic acid (9-hexadecenoic acid), stearic acid(octadecanoic acid), oleic acid (9-octadecenoic acid), ricinoleic acid(12-hydroxy-9-octadecenoic acid), vaccenic acid (11-octadecenoic acid),linoleic acid (9,12-octadecadienoic acid), alpha-linolenic acid(9,12,15-octadecatrienoic acid), gamma-linolenic acid(6,9,12-octadecatrienoic acid), arachidic acid (eicosanoic acid),gadoleic acid (9-eicosenoic acid), arachidonic acid(5,8,11,14-eicosatetraenoic acid), erucic acid (13-docosenoic acid), andmixtures thereof. In certain embodiments, the fatty acid is stearicacid. In certain embodiments, the fatty acid is behenic acid.

The percentage by weight of the fatty acid in an ink composition of theinvention can be between about 0.1% and 25%, between about 1% and 15%,or between about 2% and 10%.

The ink composition, in specific embodiments, comprises a colorant,which may be a pigment or dye, present in the ink composition in anamount of at least from about 0.1 percent to about 50 percent by weight,or at least from about 0.2 percent to about 20 percent by weight, orfrom about 0.5 percent to about 10 percent by weight of the total weightof the ink composition. In embodiments, the crystalline material ispresent an amount of from about 60 percent to about 95 percent byweight, or from about 65 percent to about 95 percent by weight, or fromabout 70 percent to about 90 percent by weight of the total weight ofthe ink composition. In embodiments, the amorphous material is presentan amount of from about 5 percent to about 40 percent by weight, or fromabout 5 percent to about 35 percent by weight, or from about 10 percentto about 30 percent by weight of the total weight of the inkcomposition.

In embodiments, in the molten state, the resulting solid ink has aviscosity of from about 1 to about 22 cps, or from about 4 to about 15cps, or from about 6 to about 12 cps, at a the jetting temperature. Thejetting temperature is typically comprised in a range from about 100° C.to about 140° C. In embodiments, the solid ink has a viscosity of about>10⁶ cps, at room temperature. In embodiments, the solid ink has aT_(melt) of from about 65 to about 140° C., or from about 70 to about140° C., from about 80 to about 135° C. and a L_(crys) of from about 40to about 140° C., or from about 45 to about 130° C., from about 50 toabout 120° C., as determined by DSC at a rate of 10° C./min.

The ink of embodiments may further include conventional additives totake advantage of the known functionality associated with suchconventional additives. Such additives may include, for example, atleast one antioxidant, defoamer, slip and leveling agents, clarifier,viscosity modifier, adhesive, plasticizer and the like.

The ink may optionally contain antioxidants to protect the images fromoxidation and also may protect the ink components from oxidation whileexisting as a heated melt in the ink reservoir. Examples of suitableantioxidants include N,N′-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) (IRGANOX 1098, available from BASF),2,2-bis(4-(2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy))ethoxyphenyl)propane(TOPANOL-205, available from Vertullus),tris(4-tert-butyl-3-hydroxy-2,6-dimethyl benzyl)isocyanurate (Aldrich),2,2′-ethylidene bis(4,6-di-tert-butylphenyl)fluoro phosphonite(ETHANOX-398, available from Albermarle Corporation),tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenyl diphosphonite (Aldrich),pentaerythritol tetrastearate (TCI America), tributylammoniumhypophosphite (Aldrich), 2,6-di-tert-butyl-4-methoxyphenol (Aldrich),2,4-di-tert-butyl-6-(4-methoxybenzyl)phenol (Aldrich),4-bromo-2,6-dimethylphenol (Aldrich), 4-bromo-3,5-didimethylphenol(Aldrich), 4-bromo-2-nitrophenol (Aldrich),4-(diethylaminomethyl)-2,5-dimethylphenol (Aldrich),3-dimethylaminophenol (Aldrich), 2-amino-4-tert-amylphenol (Aldrich),2,6-bis(hydroxymethyl)-p-cresol (Aldrich), 2,2′-methylenediphenol(Aldrich), 5-(diethylamino)-2-nitrosophenol (Aldrich),2,6-dichloro-4-fluorophenol (Aldrich), 2,6-dibromo fluoro phenol(Aldrich), α-trifluoro-o-creso-1 (Aldrich), 2-bromo-4-fluorophenol(Aldrich), 4-fluorophenol (Aldrich),4-chlorophenyl-2-chloro-1,1,2-tri-fluoroethyl sulfone (Aldrich),3,4-difluoro phenylacetic acid (Adrich), 3-fluorophenylacetic acid(Aldrich), 3,5-difluoro phenylacetic acid (Aldrich),2-fluorophenylacetic acid (Aldrich), 2,5-bis(trifluoromethyl)benzoicacid (Aldrich),ethyl-2-(4-(4-(trifluoromethyl)phenoxy)phenoxy)propionate (Aldrich),tetrakis (2,4-di-tert-butyl phenyl)-4,4′-biphenyl diphosphonite(Aldrich), 4-tert-amyl phenol (Aldrich),3-(2H-benzotriazol-2-yl)-4-hydroxy phenethylalcohol (Aldrich), NAUGARD76, NAUGARD 445, NAUGARD 512, AND NAUGARD 524 (manufactured by ChemturaCorporation), and the like, as well as mixtures thereof. Theantioxidant, when present, may be present in the ink in any desired oreffective amount, such as from about 0.25 percent to about 10 percent byweight of the ink or from about 1 percent to about 5 percent by weightof the ink.

Phase change inks for color printing typically comprise a phase changeink carrier composition which is combined with a phase change inkcompatible colorant. In a specific embodiment, a series of colored phasechange inks can be formed by combining ink carrier compositions withcompatible subtractive primary colorants. The subtractive primarycolored phase change inks can comprise four component dyes or pigments,namely, cyan, magenta, yellow and black, although the inks are notlimited to these four colors. These subtractive primary colored inks canbe formed by using a single dye or pigment or a mixture of dyes or amixture of pigments.

In embodiments, the phase change ink compositions described herein alsoinclude a colorant. The ink of the present embodiments can thus be onewith or without colorants. Any desired or effective colorant can beemployed in the phase change ink compositions, including dyes, pigments,mixtures thereof, and the like, provided that the colorant can bedissolved or dispersed in the ink carrier. Any dye or pigment may bechosen, provided that it is capable of being dispersed or dissolved inthe ink carrier and is compatible with the other ink components. Thephase change carrier compositions can be used in combination withconventional phase change ink colorant materials, such as Color Index(C.I.) Solvent Dyes, Disperse Dyes, modified Acid and Direct Dyes, BasicDyes, Sulphur Dyes, Vat Dyes, and the like. Examples of suitable dyesinclude Neozapon Red 492 (BASF); Orasol Red G (Pylam Products); DirectBrilliant Pink B (Oriental Giant Dyes); Direct Red 3BL (ClassicDyestuffs); Supranol Brilliant Red 3BW (Bayer AG); Lemon Yellow 6G(United Chemie); Light Fast Yellow 3G (Shaanxi); Aizen Spilon YellowC-GNH (Hodogaya Chemical); Bemachrome Yellow GD Sub (Classic Dyestuffs);Cartasol Brilliant Yellow 4GF (Clariant); Cibanone Yellow 2G (ClassicDyestuffs); Orasol Black RLI (BASF); Orasol Black CN (Pylam Products);Savinyl Black RLSN(Clariant); Pyrazol Black BG (Clariant); Morfast Black101 (Rohm & Haas); Diaazol Black RN (ICI); Thermoplast Blue 670 (BASF);Orasol Blue GN (Pylam Products); Savinyl Blue GLS (Clariant); Luxol FastBlue MBSN (Pylam Products); Sevron Blue 5GMF (Classic Dyestuffs);Basacid Blue 750 (BASF); Keyplast Blue (Keystone Aniline Corporation);Neozapon Black X51 (BASF); Classic Solvent Black 7 (Classic Dyestuffs);Sudan Blue 670 (C.I. 61554) (BASF); Sudan Yellow 146 (C.I. 12700)(BASF); Sudan Red 462 (C.I. 26050) (BASF); C.I. Disperse Yellow 238;Neptune Red Base NB543 (BASF, C.I. Solvent Red 49); Neopen Blue FF-4012(BASF); Lampronol Black BR (C.I. Solvent Black 35) (ICI); Morton MorplasMagenta 36 (C.I. Solvent Red 172); metal phthalocyanine colorants suchas those disclosed in U.S. Pat. No. 6,221,137, the disclosure of whichis totally incorporated herein by reference, and the like. Polymericdyes can also be used, such as those disclosed in, for example, U.S.Pat. No. 5,621,022 and U.S. Pat. No. 5,231,135, the disclosures of eachof which are herein entirely incorporated herein by reference, andcommercially available from, for example, Milliken & Company as MillikenInk Yellow 869, Milliken Ink Blue 92, Milliken Ink Red 357, Milliken InkYellow 1800, Milliken Ink Black 8915-67, uncut Reactint Orange X-38,uncut Reactint Blue X-17, Solvent Yellow 162, Acid Red 52, Solvent Blue44, and uncut Reactint Violet X-80.

Pigments are also suitable colorants for the phase change inks. Examplesof suitable pigments include PALIOGEN Violet 5100 (BASF); PALIOGENViolet 5890 (BASF); HELIOGEN Green L8730 (BASF); LITHOL Scarlet D3700(BASF); SUNFAST Blue 15:4 (Sun Chemical); Hostaperm Blue B2G-D(Clariant); Hostaperm Blue B4G (Clariant); Permanent Red P-F7RK;Hostaperm Violet BL (Clariant); LITHOL Scarlet 4440 (BASF); Bon Red C(Dominion Color Company); ORACET Pink RF (BASF); PALIOGEN Red 3871 K(BASF); SUNFAST Blue 15:3 (Sun Chemical); PALIOGEN Red 3340 (BASF);SUNFAST Carbazole Violet 23 (Sun Chemical); LITHOL Fast Scarlet L4300(BASF); SUNBRITE Yellow 17 (Sun Chemical); HELIOGEN Blue L6900, L7020(BASF); SUNBRITE Yellow 74 (Sun Chemical); SPECTRA PAC C Orange 16 (SunChemical); HELIOGEN Blue K6902, K6910 (BASF); SUNFAST Magenta 122 (SunChemical); HELIOGEN Blue D6840, D7080 (BASF); Sudan Blue OS (BASF);NEOPEN Blue FF4012 (BASF); PV Fast Blue B2GO1 (Clariant); IRGALITE BlueGLO (BASF); PALIOGEN Blue 6470 (BASF); Sudan Orange G (Aldrich), SudanOrange 220 (BASF); PALIOGEN Orange 3040 (BASF); PALIOGEN Yellow 152,1560 (BASF); LITHOL Fast Yellow 0991 K (BASF); PALIOTOL Yellow 1840(BASF); NOVOPERM Yellow FGL (Clariant); Ink Jet Yellow 4G VP2532(Clariant); Toner Yellow HG (Clariant); Lumogen Yellow D0790 (BASF);Suco-Yellow L1250 (BASF); Suco-Yellow D1355 (BASF); Suco Fast YellowD1355, D1351 (BASF); HOSTAPERM Pink E 02 (Clariant); Hansa BrilliantYellow 5GX03 (Clariant); Permanent Yellow GRL 02 (Clariant); PermanentRubine L6B 05 (Clariant); FANAL Pink D4830 (BASF); CINQUASIA Magenta (DUPONT); PALIOGEN Black L0084 (BASF); Pigment Black K801 (BASF); andcarbon blacks such as REGAL 330™ (Cabot), Nipex 150 (Evonik) CarbonBlack 5250 and Carbon Black 5750 (Columbia Chemical), and the like, aswell as mixtures thereof.

Pigment dispersions in the ink base may be stabilized by synergists anddispersants. Generally, suitable pigments may be organic materials orinorganic. Magnetic material-based pigments are also suitable, forexample, for the fabrication of robust Magnetic Ink CharacterRecognition (MICR) inks. Magnetic pigments include magneticnanoparticles, such as for example, ferromagnetic nanoparticles.

Also suitable are the colorants disclosed in U.S. Pat. No. 6,472,523,U.S. Pat. No. 6,726,755, U.S. Pat. No. 6,476,219, U.S. Pat. No.6,576,747, U.S. Pat. No. 6,713,614, U.S. Pat. No. 6,663,703, U.S. Pat.No. 6,755,902, U.S. Pat. No. 6,590,082, U.S. Pat. No. 6,696,552, U.S.Pat. No. 6,576,748, U.S. Pat. No. 6,646,111, U.S. Pat. No. 6,673,139,U.S. Pat. No. 6,958,406, U.S. Pat. No. 6,821,327, U.S. Pat. No.7,053,227, U.S. Pat. No. 7,381,831 and U.S. Pat. No. 7,427,323, thedisclosures of each of which are incorporated herein by reference intheir entirety.

The colorant may be present in the phase change ink in any desired oreffective amount to obtain the desired color or hue such as, forexample, at least from about 0.1 percent by weight of the ink to about50 percent by weight of the ink, at least from about 0.2 percent byweight of the ink to about 20 percent by weight of the ink, and at leastfrom about 0.5 percent by weight of the ink to about 10 percent byweight of the ink.

In embodiments, the phase change inks may have melting points of fromabout 65° C. to about 140° C., for example from about 70° C. to about140° C., from about 75° C. to about 135° C., from about 80° C. to about130° C., or from about 85° C. to about 125° C. as determined by, forexample, differential scanning calorimetry at a rate of 10° C./min.

In embodiments, the phase change inks may have a jetting viscosity ofabout 1 cps to about 22 cps, such as from about 5 cps to about 15 cps,from about 8 cps to about 12 cps, at the jetting temperature which iscomprised in a range from of about 100° C. to about 140° C.

The ink compositions can be prepared by any desired or suitable method.For example, each of the components of the ink carrier can be mixedtogether, followed by heating, the mixture to at least its meltingpoint, for example from about 60° C. to about 150° C., 80° C. to about145° C., and 85° C. to about 140° C. The colorant may be added beforethe ink ingredients have been heated or after the ink ingredients havebeen heated. When pigments are the selected colorants, the moltenmixture may be subjected to grinding in an attritor or ball millapparatus or other high energy mixing equipment to affect dispersion ofthe pigment in the ink carrier. The heated mixture is then stirred forabout 5 seconds to about 30 minutes or more, to obtain a substantiallyhomogeneous, uniform melt, followed by cooling the ink to ambienttemperature (typically from about 20° C. to about 25° C.). The inks aresolid at ambient temperature. In a specific embodiment, during theformation process, the inks in their molten state are poured into moldsand then allowed to cool and solidify to form ink sticks. Suitable inkpreparation techniques are disclosed in U.S. Pat. No. 7,186,762, thedisclosure of which is incorporated herein by reference in its entirety.

The inks can be employed in apparatus for direct printing ink jetprocesses and in indirect (offset) printing ink jet applications.Another embodiment disclosed herein is directed to a process whichcomprises incorporating an ink as disclosed herein into an ink jetprinting apparatus, melting the ink, and causing droplets of the meltedink to be ejected in an imagewise pattern onto a recording substrate. Adirect printing process is also disclosed in, for example, U.S. Pat. No.5,195,430, the disclosure of which is totally incorporated herein byreference. Yet another embodiment disclosed herein is directed to aprocess which comprises incorporating an ink as disclosed herein into anink jet printing apparatus, melting the ink, causing droplets of themelted ink to be ejected in an imagewise pattern onto an intermediatetransfer member, and transferring the ink in the imagewise pattern fromthe intermediate transfer member to a final recording substrate. In aspecific embodiment, the intermediate transfer member is heated to atemperature above that of the final recording sheet and below that ofthe melted ink in the printing apparatus. In another specificembodiment, both the intermediate transfer member and the finalrecording sheet are heated; in this embodiment, both the intermediatetransfer member and the final recording sheet are heated to atemperature below that of the melted ink in the printing apparatus; inthis embodiment, the relative temperatures of the intermediate transfermember and the final recording sheet can be (1) the intermediatetransfer member is heated to a temperature above that of the finalrecording substrate and below that of the melted ink in the printingapparatus; (2) the final recording substrate is heated to a temperatureabove that of the intermediate transfer member and below that of themelted ink in the printing apparatus; or (3) the intermediate transfermember and the final recording sheet are heated to approximately thesame temperature. An offset or indirect printing process is alsodisclosed in, for example, U.S. Pat. No. 5,389,958, the disclosure ofwhich is totally incorporated herein by reference. In one specificembodiment, the printing apparatus employs a piezoelectric printingprocess wherein droplets of the ink are caused to be ejected inimagewise pattern by oscillations of piezoelectric vibrating elements.Inks as disclosed herein can also be employed in other hot melt printingprocesses, such as hot melt acoustic ink jet printing, hot melt thermalink jet printing, hot melt continuous stream or deflection ink jetprinting, and the like. Phase change inks as disclosed herein can alsobe used in printing processes other than hot melt ink jet printingprocesses.

Any suitable substrate or recording sheet can be employed, includingcoated and plain paper. Coated paper includes silica coated papers suchas Sharp Company silica coated paper, JuJo paper, HAMMERMILL LASERPRINTpaper, and the like, glossy coated papers such as XEROX Digital ColorElite Gloss, Sappi Warren Papers LUSTROGLOSS, specialty papers such asXerox DURAPAPER, and the like. Plain paper includes such as XEROX 4200papers, XEROX Image Series papers, Courtland 4024 DP paper, rulednotebook paper, bond paper. Transparency materials, fabrics, textileproducts, plastics, polymeric films, inorganic recording mediums such asmetals and wood, may also be used.

Such robust inks may be used with printing equipment at high speeds.Typically, production digital presses print at a speed comprised fromabout 100 to 500 or more feet/minute. This requires inks which arecapable of solidifying very fast once placed onto the paper, in order toprevent offset of the printed image during fast printing process, whereprinted paper is either stacked (cut-sheet printers) or rolled(continuous feed printers). Fast crystallization is not a general orinherent property of crystalline-amorphous robust inks. Therefore notall crystalline-amorphous inks are suitable for fast printing.

In order to evaluate the suitability of a test ink for fast printing aquantitative method for measuring the rates of crystallization of solidinks containing crystalline components was developed. TROM(Time-Resolved Optical Microscopy) enables comparison between varioustest samples and, as a result, is a useful tool for monitoring theprogress made with respect to the design of fast crystallizing inks.

TROM is described in co-pending U.S. patent application Ser. No. ______(not yet assigned) entitled “TROM Process for Measuring the Rate ofCrystallization of Solid Inks” to Gabriel Iftime et al., electronicallyfiled on the same day herewith (Attorney Docket No. 20110828-401275),

Time Resolved Optical Microscopy

TROM monitors the appearance and the growth of crystals by usingPolarized Optical Microscopy (POM). The sample is placed between crossedpolarizers of the microscope. Crystalline materials are visible becausethey are birefringent. Amorphous materials or liquids, similar to, forexample, inks in their molten state that do not transmit light, appearblack under POM. Thus, POM enables an image contrast when viewingcrystalline components and allows for pursuing crystallization kineticsof crystalline-amorphous inks when cooled from the molten state to aset-temperature. Polarized optical microscopy (POM) enables exceptionalimage contrast when viewing crystalline components.

In order to obtain data that allow comparison between different andvarious samples, standardized TROM experimental conditions were set,with the goal of including as many parameters relevant to the actualprinting process.

The key set parameters include:

(a) glass slides of a 16-25 mm diameter and a thickness comprise inbetween 0.2 mm to 0.5 mm.(b) ink sample thickness comprised in a range from 5 to 25 microns(c) cooling temperature set at 40° C.

For rate of crystallization measurement, the sample is heated to theexpected jetting temperature (viscosity=10-12 cps) via an offlinehotplate and then transferred to a cooling stage coupled with an opticalmicroscope. The cooling stage is thermostated at a preset temperaturewhich is maintained by controlled supply of heat and liquid nitrogen.This experimental set-up models the expected drum/paper temperature ontowhich a drop of ink would be jetted in real printing process (40° C. forthe experiments reported herein). Crystal formation and growth isrecorded with a camera.

The key steps in the TROM process are illustrated in FIG. 1,highlighting the key steps in the measuring process with the mainlineink base which contains just amorphous and crystalline components (nodye or pigment). When viewed under POM, the molten and at time zero, thecrystalline-amorphous inks appear black as no light is passed through.As the sample crystallizes, the crystalline areas appear brighter. Thenumbers reported by TROM include: the time from the first crystal(crystallization onset) to the last (crystallization completion).

The definition of key measured parameters of the TROM process are setforth below:

-   -   Time zero (T=0 s)−the molten sample is placed on the cooling        stage under microscope    -   T onset=the time when the first crystal appears    -   T growth=the duration of the crystal growth from the first        crystal (T onset) to the completion of the crystallization (T        total)    -   T total=T onset+T growth

It should be understood that the crystallization times obtained with theTROM method for selected inks are not identical to what would be thecrystallization times of a droplet of ink in an actual printing device.In an actual printing device such as a printer, the ink solidifies muchfaster. We determined that there is a good correlation between the totalcrystallization time as measured by the TROM method and thesolidification time of an ink in a printer. In the standardizedconditions described above, we determined that inks solidify within10-15 seconds or less measured by the TROM method, are suitable for fastprinting, typically at speeds from 100 feet/minute or higher. Therefore,for the purpose of the present disclosure, a rate of crystallizationlower than 15 seconds is considered to be fast crystallizing.

In certain embodiments, the phase change ink crystallizes in less than15 seconds.

The inks described herein are further illustrated in the followingexamples. All parts and percentages are by weight unless otherwiseindicated.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also,various presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art, and are also intended to beencompassed by the following claims.

While the description above refers to particular embodiments, it will beunderstood that many modifications may be made without departing fromthe spirit thereof. The accompanying claims are intended to cover suchmodifications as would fall within the true scope and spirit ofembodiments herein.

The presently disclosed embodiments are, therefore, to be considered inall respects as illustrative and not restrictive, the scope ofembodiments being indicated by the appended claims rather than theforegoing description. All changes that come within the meaning of andrange of equivalency of the claims are intended to be embraced therein.

EXAMPLES

The examples set forth herein below and are illustrative of differentcompositions and conditions that can be used in practicing the presentembodiments. All proportions are by weight unless otherwise indicated.It will be apparent, however, that the present embodiments can bepracticed with many types of compositions and can have many differentuses in accordance with the disclosure above and as pointed outhereinafter.

Example 1 Preparation of Ink Samples

Sample 1 (Ink base):

Di-DL-menthyl L-tartrate (DMT) was used as the amorphous compound andDi-phenethyl L-tartrate (DPT) was used as the crystalline compound inthe ink. The mixture of DMT (10 g, 20 wt %) and DPT (40 g, 80 wt %) werestirred in the molten state at 140° C. without dye, then cooled down toobtain the ink base sample.

Sample 2:

Ink base sample 1 (2.375 g, 95 wt %) and stearic acid (0.125 g, 5 wt %)were combined and stirred at 140° C. for 1 h. The mixture was dischargedinto an aluminum pan and allowed to cool.

Sample 3:

Ink base sample 1 (2.375 g, 95 wt %) and behenic acid (0.125 g, 5 wt %)were combined and stirred at 140° C. for 1 h. The mixture was dischargedinto an aluminum pan and allowed to cool.

Sample 4:

DPT (176.4 g, 78.4 wt %) and DMT (44.1 g, 19.6 wt %) were combined andstirred at 140° C. for 1 h. To this solution was added Solvent Blue 101(4.5 g, 2 wt %). The complete ink was stirred for an additional 1 h at140° C. before filtering through a 5 μm metal sieve. The ink wasdischarged into an aluminum pan and allowed to cool.

Sample 5:

Sample 4 (2.375 g, 95 wt %) and stearic acid (0.125 g, 5 wt %) werecombined and stirred at 140° C. for 1 h. The sample was discharged intoan aluminum pan and allowed to cool.

Table 1 shows the rate of crystallization for control inks (samples 1and 4) containing no fatty acid additives, and ink samples 2, 3, and 5containing fatty acid additives. Sample 1 contains no fatty acid with ameasured crystallization time of 24 s. The measured crystallization timereduced to 14 s with the addition of 5% stearic acid (sample 2), and 7 swith the addition of 5% behenic acid (sample 3).

To ink sample 1 was added a colorant, solvent blue 101 dye (SB101), thecrystallization time increased substantially to 145 s (sample 4).Surprisingly, when a fatty acid such as stearic acid was added to thesame ink sample (sample 4), the crystallization time reduced to 14 s (10times reduction) which represents a significant advancement.

TABLE 1 Ttest Sample Formulation (° C.) T onset (s) T growth(s) T total(s) 1 Ink Base: DPT 120 3 21 24 (80%) + DMT (20%) 2 Ink Base: DPT + 1203 11 14 DMT (95%) from #1 Stearic acid (5%) 3 Ink Base: DPT + 120 5 2 7DMT (95%) from #1 Behenic acid (5%) 4 Ink: (DPT + 120 7 138 145 DMT)from #1 (98%) + SB101 dye (2%) 5 Ink sample 4 120 6 8 14 (95%) Stearicacid (5%) * T_(test) = temperature at which the ink is melted fortesting. This temperature is, in general, the expected jettingtemperature, typically the temperature at which the ink has a viscosityof about 10-12 cps.

The claims, as originally presented and as they may be amended,encompass variations, alternatives, modifications, improvements,equivalents, and substantial equivalents of the embodiments andteachings disclosed herein, including those that are presentlyunforeseen or unappreciated, and that, for example, may arise fromapplicants/patentees and others. Unless specifically recited in a claim,steps or components of claims should not be implied or imported from thespecification or any other claims as to any particular order, number,position, size, shape, angle, color, or material.

All the patents and applications referred to herein are herebyspecifically, and totally incorporated herein by reference in theirentirety in the instant specification.

What is claimed is: 1-19. (canceled)
 20. A phase change ink comprising:an amorphous compound being bis(2-isopropyl-5-methylcyclohexyl)L-tartrate); a crystalline compounds selected from the group consistingof dibenzyl L-tartrate, diphenethyl L-tartrate, bis(3-phenyl-1-propyl)L-tartrate, bis(2-phenoxyethyl) L-tartrate, diphenyl L-tartrate,bis(4-methylphenyl) L-tartrate, bis(4-methoxylphenyl) L-tartrate,bis(4-methylbenzyl) L-tartrate, bis(4-methoxylbenzyl) L-tartrate,dicyclohexyl L-tartrate, and any stereoisomers and mixtures thereof; anda fatty acid.
 21. The phase change ink of claim 20, wherein thecrystalline compound is present in an amount of from 60 percent to 95percent by weight of the total weight of the phase change ink.
 22. Thephase change ink of claim 20, wherein the amorphous compound is presentin an amount of from 5 percent to 40 percent by weight of the totalweight of the phase change ink.
 23. The phase change ink of claim 20,wherein the crystalline compound/amorphous compound ratio is from 60:40to 95:5.
 24. The phase change ink of claim 20, wherein the fatty acid isselected from the group consisting of palmitic acid (hexadecanoic acid),palmitoleic acid (9-hexadecenoic acid), stearic acid (octadecanoicacid), oleic acid (9-octadecenoic acid), ricinoleic acid(12-hydroxy-9-octadecenoic acid), vaccenic acid (11-octadecenoic acid),linoleic acid (9,12-octadecadienoic acid), alpha-linolenic acid(9,12,15-octadecatrienoic acid), gamma-linolenic acid(6,9,12-octadecatrienoic acid), arachidic acid (eicosanoic acid),gadoleic acid (9-eicosenoic acid), arachidonic acid(5,8,11,14-eicosatetraenoic acid), erucic acid (13-docosenoic acid), andmixtures thereof.
 25. The phase change ink of claim 20, wherein thefatty acid comprises stearic acid or behenic acid.
 26. The phase changeink of claim 20, wherein the fatty acid is present in an amount of from0.1% to 25% by weight based on the entire phase change ink.
 27. Thephase change ink of claim 20 having a viscosity of less than 22 cps at atemperature of 140° C.
 28. The phase change ink of claim 20 having aviscosity of greater than about 10⁶ cps at room temperature.
 29. Thephase change ink of claim 20, wherein the phase change ink crystallizesin less than 15 seconds.